When attaching implants, such as, for example, artificial knee, elbow, finger or hip joints, it is necessary to position the implant as exactly as possible on the adjacent bone. To this end, incisions and/or bores are made, typically on the bone structures adjacent to the implant.
For example, a precise incision on the bone is necessary in knee arthroplasty to achieve maximum stability and resilience of the implant. To this end, a tool, such as an incision block, serves as a template for the cutting process and must be precisely placed on the bone in order to achieve an exact resection. Once placed on the bone, the incisions are made and the implant can be attached to the bone.
Computer-assisted surgery (CAS) is a tool often used by surgeons to assist during surgical procedures. When using CAS, the bone structure of the patient is known to a navigation system following a reading-in procedure. CAS, via a display, provides visual feedback to the surgeon of the location of the bone with respect to tools and/or instruments, such as incision blocks and/or other devices (e.g., stability rods, tools, clamps and the like, any of which may be external to the bone structure or run intramedullarily in the bone). The surgeon uses the visual feedback to place or otherwise position the incision block on the bone such that cutting planes formed by the incision block are in a desired location. Moreover, CAS allows the surgeon to view the location of the other devices on or in the bone structure with respect to the cutting planes of the incision block. In doing so, the surgeon can avoid placing the incision block such that the cutting planes intersect or otherwise encroach the devices on or in the bone.
For example, during surgery the surgeon places the incision block on the bone by freehand and, once in the desired location, the surgeon fixes the incision block to the bone. More particularly, the surgeon places the incision block on the bone and, using the visual feedback provided by the CAS, alters the angle, position, etc. of the incision block with respect to the bone such that one or more cutting planes of the incision block are in a desired location. Once the cutting planes are in the desired location, the incision block is rigidly fastened to the bone using fastening means, such as screws, nails or the like.
Unfortunately, it often is difficult to maintain the precise position of the incision block as it is fastened to the bone. Often, the final precision of the incision block placement depends on the ability of the surgeon, despite the assistance of CAS.
Accordingly, it would be advantageous to provide an apparatus wherein the final position of the tool is independent of the surgeon's abilities.